JP7406588B2 - Manufacturing method of foam laminated sheet - Google Patents

Description

The present invention relates to a method for manufacturing a foam laminate sheet.

A foam molded into a sheet (foam sheet) usually has high cushioning properties and good followability to unevenness. Furthermore, foam sheets not only improve airtightness by adopting a so-called closed-cell foam structure (increase water permeability and air permeability by adopting a so-called open-cell foam structure), but also contain certain additives. By adding , it is possible to improve electrical conductivity, thermal conductivity, hydrophilicity, etc. In this way, the foam sheet is a functional material that can be imparted with various properties depending on the conditions and applications in which it is used.

Here, in a foamed sheet, a skin layer (also referred to as a skin layer) without air bubbles is usually formed on both surfaces of the sheet in the process of molding a composition that is a raw material of the foam into a sheet shape. This skin layer is hard due to its high density, resulting in a decrease in cushioning properties and ability to follow fine irregularities. Therefore, in order to ensure cushioning properties and conformability to irregularities, the skin layer may be divided and removed by splitting or the like, and only the core portion without the skin layer may be used as a foam sheet.

In Patent Document 1, the constituent materials of the cushioning material before foaming and the constituent materials of the foamed resin base material before foaming are simultaneously extruded and laminated, and the cushioning material and the foamed resin base material are laminated at the same time or immediately after the extrusion molding. By foaming at the same time, it has a sufficient foaming ratio but does not cause deformation such as warping, bending, or twisting, and does not require specially effective materials, and the layering of cushioning materials can be done efficiently. A method of manufacturing a foamed resin molded article that can be carried out is disclosed.

JP2009-56650

However, when a foamed sheet is molded according to the method of Patent Document 1, structural irregularities including the presence of pinholes (air bubbles that penetrate through the thickness of the sheet) occur, which affects not only the appearance but also the mechanical properties. There were also problems with the nature.

Therefore, an object of the present invention is to provide a foam sheet that is less likely to have structural irregularities including pinholes.

The present inventors conducted extensive research based on the above-mentioned problems, and found that the above-mentioned problems could be solved by subjecting a plurality of foam sheets to a specific treatment to make a foam laminated sheet, and completed the present invention. . That is, the present invention is as follows.

The present invention (1) is
A method for manufacturing a foam laminated sheet, the method comprising:
a lamination step of laminating a plurality of foam sheets to form a laminate;
a thermocompression bonding step of thermocompression bonding the laminate at a temperature above the softening point and below the melting point of the plurality of foam sheets constituting the laminate;
A method for manufacturing a foamed laminated sheet, comprising:
The present invention (2) is
The manufacturing method according to the invention (1), wherein one or both of the foam sheets does not have a skin layer on the contact surface of each pair of layers of the plurality of foam sheets constituting the laminate.
The present invention (3) is
The invention (1), wherein a part or all of the plurality of foamed sheets constituting the laminate are obtained by dividing a foamed sheet original fabric in the thickness direction so as to become a plurality of divided foamed sheets. ) or (2).
The present invention (4) is
The foamed sheet material is a sheet obtained by foaming a resin composition containing at least a resin,
an impregnation step of impregnating the molten resin composition with the substance in a supercritical or subcritical state under conditions that maintain the supercritical or subcritical state of the substance that is a gas at room temperature and normal pressure;
A foamed sheet manufacturing process including a foaming step of foaming the resin composition by placing the resin composition impregnated with the substance under conditions in which the supercritical state or subcritical state of the substance is not maintained. This is the manufacturing method of the above invention (3), which is a method according to the invention (3).
The present invention (5) is
Inventions (1) to (5) above, wherein there are 100 (cells/mm ² ) or more and less than 1000 (cells/mm ² ) bubbles with a bubble diameter of 10 to 200 μm on the surface of the foam sheet that does not have the skin layer. It is one of the manufacturing methods.

According to the present invention, it is possible to provide a foam sheet in which structural unevenness including pinholes is less likely to occur.

Further, according to the present invention, even under conditions where the thickness of the foam is restricted, it is also possible to improve the degree of freedom regarding design such as conformability and mechanical properties.

FIG. 1 is a schematic diagram of a sheet lamination method and a thermocompression bonding method in an example. FIG. 2 is a schematic diagram showing a method for measuring 180° peel strength in Examples.

Hereinafter, the method for producing a foam laminate sheet according to the present invention will be described in detail, but the present invention is not limited thereto.

<<<Method for manufacturing laminated foam sheet>>>
The method for producing a laminated foam sheet according to the present invention includes a lamination step of laminating a plurality of foam sheets to form a laminate, and a temperature of at least the softening point and below the melting point of the plurality of foam sheets constituting the laminate. The method includes at least a thermocompression bonding step of thermocompression bonding the laminate. Further, it is preferable that some or all of the plurality of foam sheets constituting the laminate are obtained by a foam sheet manufacturing process, and also by a foam sheet dividing process of dividing the original foam sheet in the thickness direction. It is preferable that it is obtained. The method for manufacturing a foam laminate sheet according to the present invention may include other steps as necessary.

Here, the foam sheet refers to a foam structure formed into a sheet shape. A so-called sheet refers to a single piece of thin paper or the like as a minimum unit. It also includes large waterproof cloths used for bedding and rain protection. The method of manufacturing the foamed sheet of the present invention is not limited; it may be made one by one by batch processing using a mold, or it may be made in the form of a long cloth that is continuously manufactured using an extruder. .

In addition, in the case of a foam formed into a sheet, the foam sheet (original foam sheet) subjected to the foam sheet dividing process, the foam sheet obtained by the foam sheet dividing process (foam sheet divided product), and the foam Laminated sheets and the like are sometimes simply expressed as "foamed sheets." Moreover, in some steps, the foam sheet may be wound up into a roll.

Note that the foam sheet in the present invention may be an open cell foam, but is preferably a closed cell foam. Note that the closed-cell foam shown here does not mean only those in which all the cells are completely independent, but some of the cells may communicate with adjacent cells, and the closed-cell foam as a whole does not mean that all the cells are completely independent. It is sufficient that each cell is independent enough to be considered a foam. Further, within the range that does not impede the effects of the present invention, a foam sheet that is an open cell foam may be further laminated on the foam sheet that is a closed cell foam.

Each of the above-mentioned steps will be explained below.

<<Foam sheet manufacturing process>>
The foam sheet manufacturing process is a process of manufacturing a foam sheet used in a lamination process or a foam sheet dividing process, and a conventionally known foam sheet manufacturing process can be applied. As the foam sheet manufacturing process, it is preferable to use a supercritical foaming method.

Hereinafter, a process for manufacturing a foamed sheet using a supercritical foaming method will be described, and then a process for manufacturing a foamed sheet using other foaming methods will be described.

Note that the foam sheet obtained by the foam sheet manufacturing process usually has skin layers on both surfaces. In the present invention, the skin layer means a layer formed on the surface layer side in the thickness direction of the foam sheet and having a relatively low foaming density and high density.

<Production process of foam sheet using supercritical foaming method>
The manufacturing process of a foamed sheet using the supercritical foaming method includes a melting process of melting the resin composition, and a condition in which the supercritical state or subcritical state of a substance that is a gas at normal temperature and normal pressure is maintained. An impregnation step in which a molten resin composition is impregnated with a substance in a supercritical state or a subcritical state (supercritical substance), and a resin composition impregnated with a supercritical substance is subjected to conditions in which the supercritical state of the supercritical substance is not maintained. and a foaming step of foaming the resin composition. Further, after foaming, a cooling step may be included in which the resin composition in a molten state is cooled and crystallized. Note that some or all of these steps may be performed simultaneously.

(melting process)
The melting step according to this embodiment is a step of melting the resin composition.

The resin composition preferably contains a thermoplastic polyolefin resin and a thermoplastic elastomer. Further, in this case, the melting step is carried out under conditions where both the polyolefin resin and the thermoplastic elastomer are melted.

The thermoplastic polyolefin resin is not particularly limited, and may be an olefin homopolymer or copolymer (random or block), or may be one type or a combination of two or more types. For example, polyolefins include polyethylene, polypropylene, polybutene-1, ethylene-propylene copolymer, ethylene-α-olefin copolymer, polymethylpentene, cyclic olefin resin, polyolefin with polar groups introduced (for example, ethylene vinyl acetate) or a combination of two or more thereof.

The thermoplastic elastomer is not particularly limited, and examples thereof include olefin-based elastomers, styrene-based thermoplastic elastomers, urethane-based elastomers, and ester-based elastomers.

The resin composition may also contain known components such as a foaming nucleating agent and other thermoplastic polymers.

The blending amount of each component can be changed as appropriate depending on the usage.

Since a substance in a supercritical or subcritical state is added and kneaded after the melting process, it is preferable that the temperature and pressure are such that the substance is in a supercritical state even in the melting process.

(Impregnation process)
The impregnation step is a step in which the molten resin composition is impregnated with the substance in a supercritical or subcritical state under conditions that maintain the supercritical or subcritical state of the substance that is a gas at room temperature and normal pressure. be.

In such a supercritical state or subcritical state, the solubility in the molten resin increases, making it possible to mix the substance at a high concentration. As a result, when there is a sudden pressure drop, more bubble nuclei are generated due to the high concentration of the substance.

Furthermore, since the substance dissolved at the molecular level is vaporized, the bubbles that are formed are minute. As a result, the density of the bubbles formed by the growth of the bubble nuclei becomes higher than in other states even if the porosity is the same.

Substances that are gases at room temperature are at room temperature (normal temperature specified by JIS Z8703, specifically 5°C or higher and 35°C or lower) and normal pressure (pressure when neither pressure is specially reduced or pressurized, specifically, for example, 86 kPa). It is not particularly limited as long as it is a gas under a pressure of 106 kPa or less, but preferably an inert gas, such as carbon dioxide or nitrogen, and more preferably a large amount of impregnated into the polyolefin resin. It is carbon dioxide that can be produced.

When carbon dioxide is selected as a substance that is a gas at normal temperature and normal pressure, the critical temperature of carbon dioxide is 31° C. and the critical pressure is 7.4 MPa. Therefore, when carbon dioxide is selected, the temperature is preferably within the range of 50 to 250°C, more preferably 90 to 230°C, and the pressure is: It is preferable to set the pressure within a range of approximately 8 to 40 MPa, and more preferably within a range of 10 to 30 MPa.

(foaming process)
The foaming process according to this embodiment is a process of foaming a resin composition impregnated with a substance that is a gas at normal temperature and pressure by placing the resin composition under conditions where the supercritical state of the substance is not maintained. .

For example, a resin composition impregnated with the substance is extruded through a die from an extrusion molding machine whose interior is at high temperature (e.g., about 155 to 180°C) and high pressure {e.g., continuously into a long sheet (e.g., around 1 mm thick). It is carried out by pushing out. That is, the resin composition is foamed while being molded into a sheet shape. A T-die or an annular die can be used as the base.

By dissolving a substance that is a gas at normal temperature and normal pressure into the resin composition under high pressure, bubble nuclei are uniformly dispersed at the molecular level.When the pressure is released under normal pressure, bubbles form from inside and become fine particles. bubbles are formed. That is, fine bubbles are formed by utilizing the solubility difference of the resin composition under pressure.

In addition, in the foaming process, it is only necessary to release the pressure, and simply extruding the resin composition from the extrusion molding machine reduces the pressure applied to the resin composition to about atmospheric pressure, so a pressure reducing device is not required. be.

In addition, as a manufacturing process of a foamed sheet using such a supercritical foaming method, you may apply the method described in patent 6025827 more specifically.

<Production process of foam sheets using other foaming methods>
As a process for manufacturing a foam sheet using other foaming methods, known methods can be applied. For example, a raw material preparation step is a step of obtaining a liquid raw material mixture containing at least an aqueous liquid dispersion medium, a water-dispersible resin, and a foaming agent; a foaming step of foaming the liquid raw material mixture to obtain a foaming mixture; Examples include a manufacturing process including a sheet forming process of forming the mixture into a sheet shape, and a drying process of evaporating the dispersion medium in the foamed mixture. Note that some or all of these steps may be performed simultaneously.

The raw materials for the liquid raw material mixture are not particularly limited as long as known ones can be used.

The means for foaming the liquid raw material mixture is not particularly limited, and any known foaming means may be used. Examples of such foaming methods include, for example, forming bubbles by blending a foaming agent that generates gas through a chemical reaction, dissolving an appropriate gas in a liquid raw material mixture under high pressure, and then lowering the pressure. A method of forming air bubbles by heating, a method of removing soluble substances mixed in a liquid raw material mixture and forming air bubbles as voids, and a method of mechanically stirring a liquid raw material mixture so that air or an appropriate gas is trapped. Examples include methods such as mechanical flossing.

The foaming conditions (temperature, time, etc.) in the foaming process can be changed as appropriate depending on the foaming means used, and the foaming density etc. can also be changed as appropriate depending on the physical properties of the foam sheet required in the lamination process. be.

The means for forming the foamed mixture into a sheet shape is not particularly limited, and any known means may be used. For example, coating using a doctor knife, doctor roll, etc. can be mentioned. Alternatively, the foamed mixture may be molded into a sheet by using an extruder or an injection molding machine.

The drying conditions in the drying step may be appropriately designed depending on the conditions of the foaming mixture and the foaming method.

The foamed sheet obtained by the foamed sheet manufacturing process is subjected to a lamination process with or without passing through a foamed sheet dividing process.

<<Foam sheet division process>>
The foamed sheet dividing step is a step in which a foamed sheet (original foamed sheet) as a raw material is divided in the thickness direction to obtain a plurality of divided foamed sheets.

More specifically, when the foam sheet original fabric is a foam sheet having skin layers on both surfaces obtained by the above-mentioned foam sheet manufacturing process, the foam sheet dividing step is a foam sheet having skin layers on only one surface. The process of dividing into two foam sheets (the process of dividing the original foam sheet into two), or two foam sheets with a skin layer only on one surface and one or more foam sheets without a skin layer. This is a dividing step (a step of dividing the original foam sheet into three or more parts).

The foamed sheet material used in the foamed sheet dividing step is not particularly limited and may be any general foamed sheet, but is preferably a foamed sheet obtained by the foamed sheet manufacturing step described above.

The method of dividing the foam sheet is not particularly limited, and for example, a band machine, a slicer, etc. can be used.

The thickness of the divided foam sheet is not particularly limited, and can be changed as appropriate depending on the thickness of the foam sheet required in the lamination process described later and the thickness of the original foam sheet from which the foam sheet is divided.

The foamed sheet dividing step may be a step of removing only the skin layer on one or both sides from the original foamed sheet.

By performing such a foam sheet dividing process, it is possible to prepare foam sheets that have a skin layer on only one side, foam sheets that do not have skin layers on both sides, etc., while having a predetermined thickness and density. can.

In addition, in the foam sheet dividing step, a foam that is thicker than a normal foam sheet may be used as the original fabric. In this case, the number of divisions may be increased so that the foam sheet divisions have the thickness required in the lamination process.

<<Lamination process>>
The lamination step is a step of laminating a plurality of foam sheets to form a laminate.

Here, at the contact surface of each pair of layers of the plurality of foam sheets constituting the laminate (for example, the contact surface between the foam sheet placed on the upper side and the foam sheet placed on the bottom side), one or both Preferably, the foam sheet does not have a skin layer. In other words, (1) in each pair of foam sheets, at least one foam sheet does not have a skin layer on both surfaces; (2) in each pair of foam sheets, at least one foam sheet does not have a skin layer on both surfaces; It is preferable that the foam sheet has a skin layer on only one surface and is laminated so that the surface of the foam sheet that does not have a skin layer is in contact with the other foam sheet. With such a configuration, it is possible to prevent air bubbles from remaining between the foam sheets in the thermocompression bonding process described below, and to improve moldability and interfacial adhesion. In addition, in order to further enhance such an effect, on the surface of the foam sheet that does not have a skin layer, the number of bubbles with a diameter of 10 to 200 μm is 100 (cells/mm ² ) or more and less than 1000 (cells/mm ² ). It is preferable to do so. Furthermore, it is more preferable that air bubbles of 50 to 150 μm exist.

Note that in order to improve followability, it is preferable to use a laminate that does not have a skin layer as the outermost layer.

The lamination method is not particularly limited, and one foam sheet may simply be placed on another foam sheet, or they may be temporarily fastened together.

The number of foam sheets (number of laminated sheets) constituting the laminate is not particularly limited, and two foam sheets or three or more foam sheets may be used. By stacking three or more layers, structural unevenness including pinholes is less likely to occur, and light shielding properties are improved. Further, the densities of the laminated foam sheets may be different from each other. Particularly in the case of a foamed laminated sheet containing a foamed sheet having open cells, pressure loss can be controlled by creating a density gradient in the sheet thickness direction.

<<Thermocompression bonding process>>
The thermocompression bonding process is a process of performing thermocompression bonding of each foam sheet at a temperature not lower than the softening point and lower than the melting point of each foam sheet constituting the laminate obtained by the lamination step. By performing such a thermocompression bonding process, a plurality of foam sheets can be integrated while maintaining the foam structure of the foam sheet to some extent.

The thermocompression bonding method is not particularly limited, and any known method can be used, such as a hot roll method. In the hot roll method, two foam sheets are laminated and rolled out, and the sheets are passed between two heated rollers with their adhesive surfaces in contact to perform thermal welding. In addition, hot air welding, hot trowel welding, hot plate welding, high frequency welder welding, and the like can be used for thermal welding.

The thermocompression bonding conditions may be such that at least the contact surfaces between the foam sheets are controlled to have a temperature that is between the softening point and the melting point (below the melting point) of each foam sheet. More specifically, the heating temperature is preferably 5 to 40°C higher than the softening point of each foam sheet and 10 to 45°C lower than the melting point of each foam sheet.

Specifically, thermocompression bonding is preferably carried out at a temperature of less than 160°C, more preferably 110°C or more and 150°C or less.

The heating time is not particularly limited, but for example, in the case of pressure bonding with a calendar roll, it is 0.085 to 0.15 seconds.

Note that the pressure conditions during thermocompression bonding can be changed as appropriate depending on the thickness of the foam sheet used and the thickness of the foam laminate sheet to be formed. For example, if thermocompression bonding is carried out with a relatively weak pressure, a foam laminated sheet can be obtained with a thickness that is not much different from the total thickness of each foam sheet, and if thermocompression bonding is carried out with a relatively strong pressure, an arbitrary It can be made into a foam laminated sheet compressed to a thickness of . The pressurizing conditions can be changed by an appropriate method such as adjusting the distance between the rolls.

In this thermocompression bonding step, the interface between each foam sheet may or may not disappear.

Note that a part or all of the lamination process (forming of the laminate) and thermocompression bonding process may be performed simultaneously. For example, the lamination process and thermocompression bonding process may be performed at the same time by pulling out a plurality of roll-shaped foam sheets from above and below, sandwiching them between rolls and hot rolling them so that they are pulled by the rolls. . In addition, by heating at least the surface of the foam sheet in advance, the foam sheet is maintained at a temperature above the softening point and below the melting point, and by laminating and pressurizing the foam sheets in that state, part of the lamination process and thermocompression bonding process can be completed. may be executed simultaneously.

Further, each of the lamination step and thermocompression bonding step may be performed multiple times. For example, a foamed laminated sheet formed through a lamination process and a thermocompression bonding process may be further laminated with another foamed sheet and then thermocompressed to form a foamed laminated sheet with an increased number of laminated layers.

By carrying out the lamination process and thermocompression bonding process as described above to laminate and integrate multiple foam sheets, the variations in each foam sheet are averaged out, making it difficult for structural unevenness to occur. . Specifically, even if a pinhole exists in one foam sheet, another foam sheet will cover the pinhole, so the occurrence of pinholes can be significantly suppressed.

In addition, by performing the lamination process and thermocompression bonding process as described above, it is possible to determine the material, density, thickness, presence or absence of a skin layer, and the arrangement of the skin layer in the laminate (of each foam sheet). The number of parameters that can be set increases, such as whether to place a skin layer between layers or whether to place a skin layer as the outermost layer of a laminate. Furthermore, since these can be easily set, the degree of freedom in designing followability, mechanical properties, etc. is improved.

<<Other processes>>
As long as the effects of the present invention are not impaired, other steps may include processing steps of shearing or perforating each sheet, washing the surface of each sheet, or surface treatment ( A treatment step of performing corona discharge treatment, antistatic treatment, anti-blocking treatment, etc.), a storage step of holding each sheet in an appropriate environment (predetermined temperature, humidity, etc.), etc. may be performed.

<<<Applications of foam laminated sheets>>>
The use of the foam laminated sheet obtained by the above manufacturing method is not particularly limited, and it is suitable for use as a shock absorbing sheet for electronic devices, a thin heat insulating sheet, a waterproof gasket, a double-sided tape base material, etc. .

<<First Example>>
<Example 1-1>
Pellets containing a polypropylene resin compound containing random polypropylene and an olefin resin containing low-density polyethylene are fed into a tandem single-screw extruder and melted in the first extruder, while carbon dioxide is brought to a supercritical state. The above pellets were impregnated into a molten resin composition and sent to a second extruder.

By expelling the molten resin composition impregnated with supercritical carbon dioxide from the mouthpiece of the second extruder and releasing the pressure all at once, a foam with a skin layer to which shear force is applied on the surface of the mouthpiece is created. A sheet (foam sheet original fabric) was obtained. The die is a circular die, and the foam is continuously produced in the form of a sheet, which is wound up into a roll as a long original foam sheet.

Next, a cutting blade having a width larger than the width of the obtained foam sheet material was prepared. The roll-shaped raw foam sheet is attached to the unwinding shaft, the cutting blade is applied between the skin layer and the foamed intermediate layer of the raw foam sheet, and the long sheet is separated from the skin layer on one side. The foamed intermediate layer was separated into two long sheets (split foamed sheets) in which the skin layer remained (skiving process). Each long sheet after the skiving process was wound up onto a roll to obtain a long sheet in which the foamed intermediate layer was exposed on one side.

Then, this long sheet with the skin layer exposed on one side and the foamed intermediate layer exposed on the other side was subjected to the skiving process again to obtain a sliced sheet with the foamed intermediate layer exposed on both sides.

Depending on the presence or absence of skiving processing and the number of times skiving is performed, foam sheet raw material (foam sheet with a skin layer on both sides), single-sided sliced product (foam sheet with skin layer on only one side), and double-sided sliced product (foam sheet with skin layer on only one side) are available. Three types of foam sheets can be prepared:

In Example 1-1, two sliced sheets (double-sided sliced products) each having a thickness of 0.35 mm were manufactured from a foam sheet material having an original thickness of 2.0 mm.

As shown in FIG. 1, the two sliced sheets were set as raw material foam sheets in two-stage feeders. Next, the two stacked raw material foam sheets were passed between two calender rolls (heating rolls) for thermocompression bonding to produce a foam laminate sheet. At this time, the surface temperature (processing temperature) of the calender roll was 130° C., the sheet feeding speed was 5 m/min, and the gap between the rolls was 0.07 mm. Note that the produced foam laminate sheet was wound up into a roll using a winding machine.

The thickness of the foamed laminated sheet after molding was 0.07 mm.

<Examples 1-2 to 1-6, Comparative Examples 1-1 to 1-3>
In the same manner as in Example 1-1, after setting the type of foam sheet to be used for thermocompression bonding (foam sheet raw material, single-sided sliced product, or double-sided sliced product) and the thickness of each foam sheet, Thermocompression bonding was performed to obtain sheets according to Examples 1-2 to 1-6 and Comparative Examples 1-1 to 1-3.

Below, the type of foam sheet and the thickness of the foam sheet used to manufacture the sheet according to each example and each comparative example, and the thickness of the sheet according to each example and each comparative example after thermocompression bonding are shown. show. For single-sided sliced products, it is also shown which surface was used as the contact surface during stacking. Further, Table 1 shows the processing temperature and feeding speed during thermocompression bonding in the production of foam laminate sheets according to each Example and each Comparative Example.

(Example 1-1)
・Foam sheet, double-sided sliced product (skinless), thickness 0.35mm
Double-sided sliced product (skinless) Thickness 0.35mm
・Thickness after thermocompression bonding: 0.07mm
(Example 1-2)
・Foam sheet, double-sided sliced product (skinless), thickness 0.35mm
Double-sided sliced product (skinless) Thickness 0.35mm
・Thickness after thermocompression bonding: 0.1mm
(Example 1-3)
・Foam sheet, double-sided sliced product (skinless), thickness 0.4mm
Double-sided sliced product (skinless) Thickness 0.4mm
・Thickness after thermocompression bonding: 0.15mm
(Example 1-4)
・Foam sheet, single-sided sliced product (single-sided skin), thickness 0.4mm
Double-sided sliced product (skinless) thickness 0.8mm
The skin surface of the single-sided sliced product was placed in contact with the double-sided sliced product.
・Thickness after thermocompression bonding: 0.15mm
(Example 1-5)
・Foam sheet, single-sided sliced product (single-sided skin), thickness 0.4mm
Double-sided sliced product (skinless) thickness 0.5mm
The skin surface of the single-sided sliced product was placed in contact with the double-sided sliced product.
・Thickness after thermocompression bonding: 0.2mm
(Example 1-6)
・Foam sheet, double-sided sliced product (skinless), thickness 0.9mm
Double-sided sliced product (skinless) Thickness 0.9mm
・Thickness after thermocompression bonding: 0.2mm
(Comparative example 1-1)
・Foam sheet, double-sided sliced product (skinless), thickness 0.6mm
・Thickness after thermocompression bonding: 0.1mm
(Comparative example 1-2)
・Foam sheet, double-sided sliced product (skinless), thickness 0.8mm
・Thickness after thermocompression bonding: 0.15mm
(Comparative example 1-3)
・Foam sheet, double-sided sliced product (skinless), thickness 0.8mm
・Thickness after thermocompression bonding: 0.2mm

Table 1 shows the thickness, density, cell diameter, cell number, and basis weight of each sheet obtained.

Note that each foam sheet material was manufactured in the same manner as in Example 1-1 except that the thickness was adjusted.

Furthermore, by changing the manufacturing conditions of the foam sheet original fabric and the skiving processing conditions, these foam sheets were made to have a desired thickness.

The thickness of the sheet after thermocompression bonding was adjusted by changing the gap of the most downstream roller.

<Evaluation>
(Appearance test)
The appearance of the sheet was observed in an area of 100 cm ² . The case where there is no pinhole/transparency is marked as ○, and the case where there is pinhole/transparency is marked as ×. Note that a hole with a diameter of 1 mm or more passing through the sheet was defined as a pinhole. In addition, the presence or absence of transparency was determined using a translucent table and a light table for visual inspection. A test piece was placed on a table and a light source was applied from the back side, and the leakage of light to the other side was visually judged.

<<Second Example>>
<Examples 2-1 to 2-3, Reference Examples 2-1 to 2-3>
Sheets according to Examples 2-1 to 2-3 and Reference Examples 2-1 to 2-3 were obtained in the same manner as in the first example.

Below, the type and thickness of the foamed sheet used to manufacture the sheet according to each Example and each Reference Example, and the thickness of the sheet according to each Example and each Comparative Example after thermocompression bonding are shown. show. For single-sided sliced products, it is also shown which surface was used as the contact surface during stacking. Further, Table 2 shows the processing temperature and feeding speed during thermocompression bonding in the production of foam laminate sheets according to each Example and each Reference Example.

(Example 2-1)
・Foam sheet Original foam sheet (double-sided skin) Thickness 1.6mm
Double-sided sliced product (skinless) Thickness 0.9mm
・Thickness after thermocompression bonding: 0.2mm
(Example 2-2)
・Foam sheet, double-sided sliced product (single-sided skin), thickness 1.3mm
Double-sided slice product (single-sided skin) thickness 1.3mm
It was placed so that the skin surface was on both outsides.
・Thickness after thermocompression bonding: 0.2mm
(Example 2-3)
・Foam sheet, double-sided sliced product (single-sided skin), thickness 1.3mm
Double-sided slice product (single-sided skin) thickness 1.3mm
It was placed so that the skin surface was on both outsides.
・Thickness after thermocompression bonding: 0.25mm
(Reference example 2-1)
・Foam sheet Original foam sheet (double-sided skin) 1.6 mm thick, 1 sheet ・Thickness after thermocompression bonding 0.15 mm
(Reference example 2-2)
・Foam sheet Original foam sheet (double-sided skin) thickness 1.6 mm, 1 sheet ・Thickness after heat compression bonding 0.2 mm
(Reference example 2-3)
・Foam sheet Original foam sheet (double-sided skin) thickness 1.6 mm, 1 sheet ・Thickness after thermo-compression bonding 0.25 mm

Table 2 shows the thickness, density, cell diameter, cell number, and basis weight of each sheet obtained.

<Evaluation>
(180° peel strength measurement method)
The 180° peel strength was measured under the following conditions. The evaluation results are shown in Table 2, and the outline of the measurement method is shown in FIG.
Double-sided adhesive tape (9671LE manufactured by 3M, thickness 50 μm) was attached to both sides of the sample.
A 25 μm thick PET film is attached to one side as a backing material to prepare a test piece.
After punching out a test piece to a width of 10 mm, it was bonded to a stainless steel plate as an adherend.
(Adhesive surface length: 60 mm) At that time, the adhesive was moved back and forth once with a 2 kg roller in an environment at room temperature to remove air from the adhered surface, and then left to cure for 30 minutes. In the test, a tensile tester (Autograph: manufactured by Shimadzu Corporation) was installed so as to achieve 180° peeling as shown in FIG. 1, and then pulled at a speed of 1,000 mm/min to measure the peel strength.
Test piece: 10mm width Backing material: PET#25
Crimping method: 2kg roller 1 round trip Crimping temperature: 23℃/50%RH
Curing conditions: 23℃/50%RH x 30min
Tensile speed: 1,000mm/min
Tensile angle: 180°
Measurement temperature: 23℃/50%RH

Note that no pinholes or see-through were observed in the sheets of Examples 2-1 to 2-3.

Claims (8)

A method for manufacturing a foam laminated sheet, the method comprising:
a lamination step of laminating a plurality of foam sheets to form a laminate;
a thermocompression bonding step of thermocompression bonding the laminate at a temperature above the softening point and below the melting point of the plurality of foam sheets constituting the laminate;
A foamed laminate sheet, wherein a part or all of the plurality of foamed sheets constituting the laminate are obtained by dividing a foamed sheet original fabric in the thickness direction so that a plurality of foamed sheet divisions are obtained. manufacturing method. A method for manufacturing a foam laminated sheet, the method comprising:
a lamination step of laminating a plurality of foam sheets to form a laminate;
a thermocompression bonding step of thermocompression bonding the laminate at a temperature above the softening point and below the melting point of the plurality of foam sheets constituting the laminate;
The foam sheet is
an impregnation step of impregnating the molten resin composition with the substance in a supercritical or subcritical state under conditions that maintain the supercritical or subcritical state of the substance that is a gas at room temperature and normal pressure;
A foamed sheet manufacturing process including a foaming step of foaming the resin composition by placing the resin composition impregnated with the substance under conditions in which the supercritical state or subcritical state of the substance is not maintained. A method of manufacturing a foam laminated sheet, which is a foamed laminated sheet. A method for manufacturing a foam laminated sheet, the method comprising:
a lamination step of laminating a plurality of foam sheets to form a laminate;
a thermocompression bonding step of thermocompression bonding the laminate at a temperature above the softening point and below the melting point of the plurality of foam sheets constituting the laminate;
A method for producing a laminated foam sheet, wherein on the surface of the foam sheet without a skin layer, there are 100 (cells/mm ² ) or more and less than 1000 (cells/mm ² ) bubbles with a bubble diameter of 10 to 200 μm. A method for manufacturing a foam laminated sheet, the method comprising:
a lamination step of laminating a plurality of foam sheets to form a laminate;
a thermocompression bonding step of thermocompression bonding the laminate at a temperature above the softening point and below the melting point of the plurality of foam sheets constituting the laminate;
A method for producing a foam laminate sheet, wherein the foam laminate sheet has a density of 250 kg/m ³ or more. A method for manufacturing a foam laminated sheet, the method comprising:
a lamination step of laminating a plurality of foam sheets to form a laminate;
a thermocompression bonding step of thermocompression bonding the laminate at a temperature above the softening point and below the melting point of the plurality of foam sheets constituting the laminate;
A method for producing a foam laminate sheet, wherein the foam laminate sheet has a thickness of 0.25 mm or less. A foam laminated sheet in which a plurality of foam sheets are laminated and integrated,
At the contact surface of the layers of each pair of the plurality of foam sheets, one or both of the foam sheets does not have a skin layer,
A foamed laminated sheet in which 100 (cells/mm ² ) or more and less than 1000 (cells/mm ² ) bubbles with a bubble diameter of 10 to 200 μm are present on the surface of the foamed sheet that does not have a skin layer. A foam laminated sheet in which a plurality of foam sheets are laminated together,
A foam laminated sheet having a density of 250 kg/m ³ or more. An article comprising the foam laminate sheet according to claim 6 or 7 ,
The article is selected from shock absorbing sheets for electronic devices, heat insulating sheets, waterproof gaskets, and double-sided tape base materials.